BACKGROUND
Throughout folliculogenesis the oocyte is surrounded by cumulus cells that regulate its growth and maturation through a series of signaling molecules transmitted via multiple gap junctions. Mitochondrial dysfunction in both the oocyte and cumulus cells can lead to impaired oocyte fertilization and ultimately result in the production of low-quality embryos in assisted reproductive technology programs. Non-invasive assessment of oocyte mitochondrial function at the current stage of technique development is not possible. However, the state of the mitochondrial network in cumulus cells could serve as a marker for the presence of oocyte mitochondrial dysfunction.
OBJECTIVE
To investigate the prognostic significance of cumulus cells mitochondrial dysfunction markers in obtaining optimal quality embryos in assisted reproductive technology protocols.
MATERIAL AND METHODS
The study included 115 women undergoing infertility treatment by using IVF. Based on the morphological characteristics of embryos, two groups were formed: group 1 (n=30) with no embryos of optimal quality obtained and group 2 (n=85) with at least 1 embryo of optimal quality obtained (Grade 2BB and higher). Using confocal microscopy, the following parameters were assessed in cumulus cell environment surrounding the oocyte: average number of mitochondria, average mitochondrial length, mitochondrial fluorescence intensity, and average fluorescence decay time.
RESULTS
No statistically significant differences in microscopy parameters were found between the groups. It was established that the increase in average number of mitochondria (OR=0.995, CI 0.923—0.988, p=0.008) and average mitochondrial length (OR=0.820, CI 0.677—0.994, p=0.043) significantly decrease the odds of obtaining embryos of optimal quality. Statistically significant negative correlations were found between the total dose of gonadotropins for controlled ovarian hyperstimulation and the average mitochondrial length and fluorescence intensity. Additionally, statistically significant negative correlations were observed between the effective dose of gonadotropins per mature oocyte and fluorescence intensity.
CONCLUSIONS
The obtained data suggest that markers of mitochondrial dysfunction, specifically the average number of mitochondria and average mitochondrial length in cumulus cells, can be used as prognostic factors for obtaining optimal quality embryos. It was established that high doses of gonadotropins negatively affect mitochondrial function.
